Spatially varying selection shapes life history clines among populations of Drosophila melanogaster from sub-Saharan Africa.

Clines in life history traits, presumably driven by spatially varying selection, are widespread. Major latitudinal clines have been observed, for example, in Drosophila melanogaster, an ancestrally tropical insect from Africa that has colonized temperate habitats on multiple continents. Yet, how geographic factors other than latitude, such as altitude or longitude, affect life history in this species remains poorly understood. Moreover, most previous work has been performed on derived European, American and Australian populations, but whether life history also varies predictably with geography in the ancestral Afro-tropical range has not been investigated systematically. Here, we have examined life history variation among populations of D. melanogaster from sub-Saharan Africa. Viability and reproductive diapause did not vary with geography, but body size increased with altitude, latitude and longitude. Early fecundity covaried positively with altitude and latitude, whereas lifespan showed the opposite trend. Examination of genetic variance-covariance matrices revealed geographic differentiation also in trade-off structure, and QST -FST analysis showed that life history differentiation among populations is likely shaped by selection. Together, our results suggest that geographic and/or climatic factors drive adaptive phenotypic differentiation among ancestral African populations and confirm the widely held notion that latitude and altitude represent parallel gradients.

Performance of parental history for the targeted screening of hypertension in children.

OBJECTIVES: Several guidelines recommend universal screening for hypertension in childhood and adolescence. Targeted screening to children with parental history of hypertension could be a more efficient strategy than universal screening. Therefore, we assessed the association between parental history of hypertension and hypertension in children, and estimated the sensitivity, specificity, negative, and positive predictive values of parental history of hypertension for hypertension in children. METHODS: The present study was a school-based cross-sectional study including 5207 children aged 10-14 years from all public 6th grade classes in the Canton of Vaud, Switzerland. Children had hypertension if they had sustained elevated blood pressure over three separate visits. RESULTS: In children, the prevalence of hypertension was 2.2%. Some 8.5% of mothers and 12.9% of fathers reported to be hypertensive. Maternal history of hypertension (odds ratio 2.0, 95% confidence interval 1.2-3.3) and paternal history of hypertension (odds ratio 2.2, 95% confidence interval 1.4-3.6) were independent risk factors for hypertension in children. Nevertheless, the sensitivity of parental history of hypertension for the identification of hypertension in children was low (from 4% for both parents' positive history up to 41% for at least one parent's positive history). Positive predictive values were also low (between 4 and 5%). CONCLUSION: Children with hypertensive parents were at higher risk of hypertension. Nevertheless, parental history of hypertension helped only marginally to identify hypertension in offspring. Targeting screening only toward children with a parental history of hypertension may not be a substantially better strategy to identify hypertension in children compared with universal screening.